Flinn is at school looking in the art cupboard for some colored pens to finish off his dinosaur drawing when he stumbles upon Captain Stubble, a real live Pirate Captain!

He tells Flinn that his ship, the Acorn, has been stolen and that he needs Flinn to help him rescue it back.

Stubble makes Flinn the captain and they sail away on an old pirate ship, and they finally find the Acorn but, to their horror, realize it's been stolen by Pirate dinosaurs!

Captain Flinn and his crew attack the dinosaurs and, after much fighting, seize control of the ship once more.

Flinn and his friends then sail back to the harbor clambering through the boatshed door and back into the art cupboard without the teacher even noticing they've been gone!